This invention relates to a machining assembly and a method of cutting a tubular member.
Conventionally, machining assemblies for machining the ends of tubular members such as pipes comprise a tubular member clamping housing into which the tubular member to be machined is clamped, and a machining housing which includes the cutting tool which machines the tubular member. In order for the tubular member to be machined, the machining housing and the clamping housing are moveable relative to one another, and usually, the movement relative to one another is controlled by a computer numerically controlled (CNC) system.
A portable machining assembly is known that provides a machining capability for the tubular member ends at the location where the tubular members are used, for example on a drilling or production onshore or offshore rig. An example of such a portable machining assembly is shown in British Patent No 2209983. This portable machining assembly has a clamping housing which clamps the tubular member in a stationary position. A machining housing is moveable in a longitudinal, and rotational direction with respect to the longitudinal axis of the tubular member, and the cutting tool, which is mounted to the machining housing, is additionally moveable in a radial direction with respect to the longitudinal axis of the tubular member. Both the longitudinal and the rotational movement of the machining housing are provided by a single motor. The motor directly drives the rotational movement of the machining housing through an intermeshing gearwheel arrangement which results in the rotational movement of the machining housing being directly fixed to the output of the motor. The longitudinal movement of the machining housing is provided through a gearbox which is selectively connectable with the machining housing. Therefore, when the motor is operating, the machining housing rotates and when longitudinal movement of the machining housing is required, the power output of the gearbox is engaged with the machining housing.
According to the present invention there is provided a machining assembly comprising a body member, and a tubular member holder for holding a tubular member;
the body member comprising a cutting tool for cutting the tubular member, the cutting tool and the tubular member being linearly moveable with respect to each other by a linear displacement mechanism, and rotationally moveable with respect to each other by a rotational movement mechanism;
the rotational movement mechanism and the linear displacement mechanism being operable by respective first and second power means, the first and second power means being controlled independently of each other, so that rotational and linear movement of the cutting tool are independent from one another.
Typically, the first and second power means comprise first and second motors.
Typically, the machining assembly further comprises a stationary housing, and preferably, the tubular member holder is secured to the stationary housing.
Typically, the body member is coupled to the stationary housing by a linearly moveable bearing arrangement.
Typically, the cutting tool and the tubular member are linearly moveable with respect to a longitudinal axis of the tubular member.
Preferably, the linear displacement mechanism comprises a screw-threaded shaft mounted on one of the stationary housing and the body member, and which is coupled to the output of the second motor, and a screw-threaded member that co-operates with the screw-threaded shaft, the screw-threaded member being mounted on the other of the stationary housing or the body member.
Typically, the screw-threaded member comprises a nut.
Preferably, the screw-threaded shaft is mounted on the stationary housing where the longitudinal axis of the screw-threaded shaft is parallel to the longitudinal axis of the tubular member.
Typically, the screw-threaded member is mounted on the body member wherein actuation of the second motor rotates the screw-threaded shaft which facilitates linear movement of the screw-threaded member.
Typically, movement of the screw-threaded member facilitates linear movement of the body member.
Typically, the body member includes a drive shaft which is rotatably mounted within the body member. Typically, a first end of the drive shaft is coupled to the first motor, and a second end of the drive shaft is coupled to the cutting tool.
Preferably, the cutting tool is moveable in a radial direction with respect to the longitudinal axis of the tubular member by a radial displacement mechanism.
According to a second aspect of the present invention there is provided a method of cutting a tubular member comprising supporting a tubular member with a tubular member holder;
providing a cutting tool;
providing for linear displacement of one of the tubular member and the cutting tool with respect to the other;
providing for rotational movement of one of the tubular member and the cutting tool with respect to the other; and
the linear displacement and rotational movement being independent of one another by use of a first and second independent power means.
Typically, actuation of the first independent power means moves one of the tubular member and the cutting tool along a longitudinal axis of the tubular member, such that the cutting tool is capable of cutting the tubular member.
Actuation of the first power means in one rotational direction typically moves the cutting tool and the tubular member linearly towards one another, and actuation of the first power means in the other direction typically moves the tubular member and the cutting tool linearly away from one another.
Typically, actuation of the second independent power means rotates one of the tubular member and the cutting tool in a clockwise direction with respect to the other.
The method may additionally comprise the step of providing for radial displacement of the cutting tool with respect to a longitudinal axis of the tubular member by use of a third independent power means.